Temporal Energy Analysis of Symbol Sequences for Fiber Nonlinear Interference Modelling via Energy Dispersion Index

The stationary statistical properties of independent, identically distributed (i.i.d.) input symbols provide insights on the induced nonlinear interference (NLI) during fiber transmission. For example, kurtosis is known to predict modulation format-dependent NLI. These can be used in design probabilistic amplitude shaping (PAS), which relies an shaper for increasing spectral efficiencies fiber-optic systems. One property certain shapers PAS—including constant-composition distribution matchers—that often overlooked that a time-dependency between amplitudes introduced. This dependency results are xmlns:xlink="http://www.w3.org/1999/xlink">non -i.i.d., have time-varying properties. Somewhat surprisingly, effective signal-to-noise ratio (SNR) PAS has been shown increase when blocklength decreases. SNR attributed symbol sequences, particular, variation energies. In this paper, we investigate temporal energy behavior and introduce new metric called xmlns:xlink="http://www.w3.org/1999/xlink">energy dispersion index (EDI). EDI captures Numerical show strong correlations SNR, with absolute correlation coefficients above 99% different transmission distances.